Phase shifters are utilized to introduce a shift in phase of an electrical signal. There are many applications for the use of phase shifters in which shifting a phase in an electrical signal is desired. As one example, phase shifters are often used in antenna arrays. Other examples include timing recovery circuits and phase equalizers for data channels.
Antenna arrays may be designed with a plurality of antennas, each transmitting and receiving an electrical feed. Phase shifters are often used to introduce a phase shift into each of the feeds. The result of introducing phase shift into each of the feeds is a steering of the resulting beam projected by the antenna. Rather than utilizing an antenna that rotates or otherwise moves, the direction at which the antenna electrically points is affected by introducing phase shift into the feeds of the antennas. This is referred to as beam steering.
Many existing phase shifters suffer from various disadvantages. For example, many phase shifters are narrow band, meaning they can operate in only a narrow range of frequencies. In addition, such phase shifters are often high loss devices or provide only a small phase shift. Such devices include monolithic microwave integrated circuit, ferroelectric, solid-state, and photonically controlled phase shifters. Beam steering methods using a ferrite plate have been developed for low cost systems but require very high voltages up to several kV. One example of such a ferrite plate shifter requires impedance matching transformers to a polarization rotator for two dimensional arrays, large size lens, power consumption of 0.5 W, and forced air cooling. In addition these phase shifters are often expensive and inefficient.